Docker Volume

#docker   #volume   #mount   #compose  

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Table of Content

Docker Volume

The purpose of using Docker volumes is to persist data outside the container so it can be backed up or shared.

bind mount

syntax

-v <source>:<destination>:<options>

simple

docker run -it \
    --rm \
    --name dev \
    -v /home/user/tmp:/app \
    ubuntu:22.04 /bin/bash

mount as readonly

docker run -it \
    --rm \
    --name dev \
    -v /home/user/tmp:/app:ro \
    ubuntu:22.04 /bin/bash

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volume mount

unnamed volume

mount volume

docker run -it --rm \
    --name dev \
    -v /app \
    ubuntu:22.04 /bin/bash 

docker volume ls
#
docker volume ls
DRIVER    VOLUME NAME
local     88a466302764f0693e60746c1f75d2b699d432bbf47de2bdc1093af49596bbba

named volume

syntax

-v <name>:<destination>:<options>

named volume

docker run -it --rm \
--name dev \
-v my_volume:/volume \
ubuntu:22.04 /bin/bash

docker volume

docker volume ls
DRIVER    VOLUME NAME
local     my_volume

Docker volumes location

/var/lib/docker/volumes/

demo: my_volume volume

docker volume inspect my_volume
[
    {
        "CreatedAt": "2023-08-10T19:57:55+03:00",
        "Driver": "local",
        "Labels": null,
        "Mountpoint": "/var/lib/docker/volumes/my_volume/_data",
        "Name": "my_volume",
        "Options": null,
        "Scope": "local"
    }
]

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Demo: volume and docker compose

• create volume: my_volume
• use volume from docker-compose

docker volume create my_volume

docker-compose up

version: "3"

services:
  demo:
    container_name: my_container_name
    image: ubuntu:22.04
    hostname: dev
    stdin_open: true 
    tty: true
    volumes:
      - my_volume:/app

volumes:
  my_volume:
    external: true # (1)

1. Declare my_volume as external value created by docker volume create

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Demo: Bind file

docker run -it \
    --rm \
    --name dev \
    -v $(pwd)/settings.yaml:/root/settings.yaml \
    ubuntu:22.04 \
    /bin/bash

source file

source file must have full path

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mount option

mount option is alternative to -v mount is more verbose and build from key, value pair

--mount type=[bind, volume, tmpfs],source=[volume_name],destination=[path_in_container], 

Note

if using mount option and mount not existing source, docker throw an error
in volume option docker well create a new source for us.

docker run -it --rm \
--name dev \
--mount type=bind,source=/home/user/tmp,destination=/app \
ubuntu:22.04 \
/bin/bash

docker inspect dev
#
# output only mount section
"Mounts": [
            {
                "Type": "bind",
                "Source": "/home/user/tmp",
                "Destination": "/app",
                "Mode": "",
                "RW": true,
                "Propagation": "rprivate"
            }
        ],

more info